Alexander wurts



(No Model.)

A. WURTS. LIGHTNING ARRESTER. No. 497,508. Patented May 16, 1893.

Figl. Fig.2.

L LC:: .1

C Q Q Q WITNESSES: INVENTOR @mm/Q iii/ m (kw/V4? Arm/mm UNITED STATESPATENT OFFICE;

ALEXANDER IVURTS, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE\VESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF SAME PLACE.

LlGHTNlNG-ARRESTER.

SPECIFICATION forming part of Letters Yatent No. 497,508, dated May 16,1893.

Application filed December 22, 1892. Serial No 456,075, (No model.)

To aZZ whom it may concern.-

Be it known that I, ALEXANDER Whats, a citizen of the United States,residing at Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new an d useful Improvement inLightning-Arresters, (Case No. 5353,13,) of .which the following is aspecification.

The object of my invention is to provide means whereby a system ofelectric wires may be rid of a static charge without providing a pathfor thedynamo current, and whereby a difference of potential may beprevented from being developed between the two branches of the circuitwhich might be sufficiently high to cause damage to the insulation ofthe armature.

Throughout this specification in speaking of difference of potential,static difference will be understood, the relatively small difference ofpotential incident to the transmission of dynamic electricity beingignored for the purposes of this description.

here an all metal circuit is to be protected and it is desired toprovide a lightning arrester for each leg of the circuit, considerabledifficulty has been experienced in so arranging the lightning arrestersthat the two legs of the circuit may be discharged at practically thesame potential. \Vhen this result is not obtained, one leg of the systemwill be discharged through the arrester before the other, and, beingmomentarily grounded, will cause a stress upon the armature insulationdue to the whole difference of potential between the undischarged legofthe system and the earth.

In the accompanying drai'vings, Figure 1 shows the best typical forms ofarr-ester in such a manner as to illustrate the difficulty abovementioned; and Fig. 2 shows my invention as applied to an all metalcircuit and exhibits the means whereby I obviate these difficulties.

In Fig. 1, let 1 be the generator and 2 and 3 the two legs of thecircuit connected respectively to the terminals 4 and 5 and adapt ed todischarge across the two air-gaps 6 and 7 to the plate 8 and so to theground. As

shown in l, the air-gap 6 seems to be greater than the air-gap '7. Thisis a difficulty which it is almost impossible to avoid in practice,inasmuch as the most careful measurement of the air-gaps at one or morepoints along the combs will not give any adequate notion of the relativeresistance to discharge on the two sides of the center plate. Vhere thisinequality is present, it is evident that even though the legs 2 and 3be charged statically at the same potential, the gap 7 being less thanthe gap 6, the leg 3 will discharge first, and will be momentarilygrounded. The consequence of this momentary ground is the establishmentof an excessive strain upon the insulation due to the difference ofpotential between theleg 2 of the system and the ground. The result ofthis stress will almost inevitably be the dismantling of the armaturethrough giving way of the insulation. My method of obviating thisdifficulty is shown in Fig. 2, wherein 2 and 3 are the two legs of thecircuit, and at 9 is shown the ordinary air-gap arrester as typical ofany form of arrester connected to only one leg 3 of the system.

Between the two legs of the system I introduce a condenser 10 for thefollowing purpose: lVhen a discharge takes place across the airgaps 9the difference of potential between 2 and 3 is immediately establishedand then compensated for by a charge of the opposite plates of thecondenser 10, and the two legs of the system are thus brought to thesame potential without any strain upon the insulation of the armature 1.The condenser 10 will hold its charge for an inappreciable time, as suchcharge will leak around through the conductors of the system with greatrapidity without endangering such conductors or any apparatus connectedto them.

hat I claim is- 1. As a means for protecting an all metal circuit fromatmospheric electricity, a lightning arrest-er connected to one leg ofthe circuit and a condenser having its opposite plates connectedrespectively with the two legs of said circuit, substantially asdescribed.

2. As a means for protecting all metal circuits from atmosphericelectricity, a connecticn from one leg of the circuit to the groundcontaining an air-gap, and a condenser having its opposite platesrespectively connected to two legs of the circuit, substantially as de-5 scribed.

3. As a means for protecting all metal circuits from atmosphericelectricity, surfaces of large capacity connected to both legs of thecircuit, and a lightning arrester connected to one leg of the circuit,substantially as (le- 10 scribed.

In testimony whereof I have hereunto subscribed my name this 20th day ofDecember, A. D. 1892.

ALEXANDER WURTS. \Vitnesses:

J AMES W. SMITH, HAROLD S. MAcKAYE.

